Qualcomm's drip-drip of Snapdragon 820 details rolls on with the Hexagon 680 DSP which will monitor step tracking and improve low-light photos.

Smartphone CPU maker Qualcomm said Monday that the Snapdragon 820's DSP, the Hexagon 680, will be Qualcomm's answer to always-on applications like step tracking and improvements in low-light photography.

Qualcomm has taken an incremental approach toward disclosing details of the Snapdragon 820, one of three key chip architectures in the smartphone space alongside Samsung's Exynos line and the Apple A-series chips. Although the 820 is scheduled to launch sometime next year, Qualcomm began disclosing the chip's core functionality in March, then details of the Adreno 530, the 820's integrated GPU. Like the Adreno, the Hexagon 680 will offload specific, repetitive functions onto the more efficient DSP engine, allowing the main core to power down and preserve the phone's battery life.

Qualcomm disclosed some of the details of the Hexagon 680 works at the Hot Chips conference. Still, the company hasn't yet disclosed the juicy details of any of its cores that smartphone fans care about: their speed, the power they consume, or their die size.

Why this matters: A dedicated "sensor core" has become a standard component of most phones: Apple built a dedicated M8 co-processor for the task, and Nokia Lumia phones have used a SensorCore component to keep track of the steps users take. Qualcomm says the DSP is optimized for the emerging, sexy applications that are selling flagship phones: virtual and augmented reality, camera processing, and monitoring sensors like pedometers and the like.

The new Hexagon 680 DSP inside the Snapdragon 820 can intelligently brighten areas of an image.

Purpose-built computing

Hexagon is actually a collection of three DSPs: a dedicated compute DSP for voice, image, and video processing, as well as computer vision; a modem DSP; and the "low power island" for always-on sensors.

The three flagship functions that the Hexagon DSP will offer, however, are improved low-light processing, computer vision, and support for the always-on, sensor-aware apps.

Qualcomm said that the DSP enables algorithms to intelligently brighten areas of photos that were underexposed a bit more intelligently than the high-dynamic range (HDR) photos that cameras take, as the algorithm intelligently lightens just regions of the photo. The Hexagon DSP uses what Qualcomm calls Hexagon Vector Extensions (HVX) to do this, providing better performance than the Snapdragon CPU itself. (Think of HVX as Qualcomm's version of the MMX instruction set that Intel microprocessors use.)

Using HVX, Qualcomm's internal data shows that its low-light video enhancement can be done with ten times less power than a quad-core Krait GPU, and three times faster to boot.